Membranes have been subject to increased investigation because of their role in cellular growth, division, and differentiation. The cell surface is also implicated in the expression of the neoplastic state, perhaps as the major phenotypic factor. Lectin-mediated agglutination, disappearance of a large surface protein (LETSP), increased fibrinolysis, increased transport of 2-deoxyglucose, and changes in morphology are expressions of the neoplastic state useful in understanding the membrane alterations involved in the transformation of normal cell behavior. We propose to study the effect of enucleation and metabolic inhibitors on the expression of these characteristics. The use of cells infected with temperature-sensitive viruses provides the necessary system to study. Rearrangement of membrane components appears to play a role in altering cell behavior. In addition, lectin-binding to cell surfaces of normal, transformed, and trypsinized cells will be re-examined by means of equilibrium dialysis. Previous binding studies have not met this requirement. The absolute number of receptor sites (Scathard plot), the heterogeneity (Sips distribution), and the thermodynamic parameters describing lectin: receptor interactions can be obtained and compared in terms of experimental cell manipulations.